Most Helpful Guy
No, I'd give him space and not prod the bear. You already described that he's having trouble moving on from your relationship and that his birthday is sort of a bad thing to him, yet you're asking if you should wish him a happy birthday? I think you need to be honest with yourself as to why you're even considering this.
Most Helpful Girl
I think you should wish him a happy birthday, it will mean a lot to him, and you will be able to make him happy for a while. Good luck!